Vergara - 1976 - Physiological and morphological adaptability of ri

CLllvL-YTIC INFLUENCE ON Pl-lO'l‘OS‘t'N'I'l-IESIS AND RESPIRATION
1. Tanaku: The sterility of the rice plant with low oxygen xvas caused by decreased germination
of pollen. If, therefore, the low oxygen treatment is conducted except in flowering time,
the rice yield may increase through the depressed photorespiration. We tested only (Iiperus
microiria. The flower of this plant has a short style. One of the reasons that Qv/zierizs micrairia
showed high fertility in low oxygen was attributable to this short style.
FlSCl-IERZ ls there any evidence that rice cultivars adapted to high altitude regions are less
sensitive to reduced oxygen than lowland cultivars? Oxygen pressure at 7.000 feet above sea
level is around 30°.» less than that at sea level.
I. Tanaka: There are some differences in photorcspiration between rice varieties. But it is
not clear that rice plants adapted to high-altitude regions are less sensitive to low oxygen.
SASTRYI Table 1 shows that in the case of Nankai 43. both P and T, 21 hours alter chilling.
tend to attain a value near the one prevailing before chilling. Can we conclude that chilling
results in a recoverable injury in Nankai 43 variety, which is more eflicient than IRS variety‘?
1. Tana/ca: Yes, the recovery of photosynthesis in chilled leaves was significantly higher in
Nankai 43 than in IR8.
hdFFCHl-ILLI 'I‘able 1 showed lower photosynthesis 4.5 hours after chilling than 3 hours after
chilling. There was a rise then at 21 hoursr Why"?
I. Tamika: Low temperature inhibits photosynthesis through inactivation of enzymes in
chloroplasts and stomatal closure by reduced water uptake. Thus. photosynthesis aflcr chilling
is primarily governed by the recovery in root activity as well as enzyrme activity in chloroplasts.
PACARDO: You claimed that rice plants sufier severe midday water deficits even if‘ they are
grown under submerged conditions. How did you measure water deficit’?
I. Tanaka." The water content in the sampled leaves was measured.